Which of the following phenomena cannot be explained by Huygens' principle?

$A$ parallel cylindrical beam of light propagates in a medium with a refractive index $\mu(I) = \mu_0 + \mu_2 I$,where $\mu_0$ and $\mu_2$ are positive constants and $I$ is the intensity. As the intensity of the light decreases,the radius increases. The initial shape of the wavefront is:

Which of the following is correct for light diverging from a point source?

$A$ light wave travels in a vacuum along the $x$-axis. Which of the following may represent the wave front?

Describe the short history of light.

$A$ plane wavefront travelling in a straight line in vacuum encounters a medium of refractive index $\mu$. At point $P,$ the shape of the wavefront is: